Strategic Defence Review: Does it Pass its Tests?

7 Jul 2025 12:22 PM

RUSI analysts have applied tests to every major strategic paper published by the UK in recent years, and now look at how the Strategic Defence Review published in June 2025 satisfies close examination.

In December 2020, RUSI published our occasional paper entitled Five Tests for the Integrated Review. The Integrated Review was then published in March 2021, and since then we have applied the same tests – to the extent that it is possible – to the Integrated Review Refresh and the Defence Command Paper Refresh in 2023, and offered them as advance ‘tests for success’ for the Strategic Defence Review (SDR) following its launch in mid-July 2024. Now, a month after its eventual publication and with the new National Security Strategy (NSS) and the NATO Summit behind us, it is timely to apply the same method to assessing the SDR’s conclusions.

To recap briefly, our tests – which we developed from our analysis of the main themes (and subsequent fates) of successive post-Cold War defence and national security reviews – were:

• Is the assessment of the risks/threats right?
• Are the proposed defence planning responses right?
• Are the proposed changes to capabilities and force structure right?
• Is there a sustainable balance between policy, commitments, the forward programme and the budget?
• Do the proposed changes to organisation/management enhance effectiveness/efficiency?

Applying these tests to the SDR is not straightforward – mainly because, meaty though it is in many respects, the SDR published on 2nd June was but a first instalment, in part a consequence of being ‘externally-led’. A range of other reviews are now catching up. The NSS, published on 24th June, reflects the conclusions of the SDR. The ‘Modern Industrial Strategy’ published the previous day aims to boost investment in a range of high-growth sectors including Defence. But we have not yet seen the new Defence Industrial Strategy, which should explain the part the Government will expect industry to play in delivering the outcome of the SDR.

More significantly from a Defence perspective, the SDR – unlike previous reviews – contains no recommended future force structure and no specific capability decisions (although a few emerged in separate announcements by the Government, such as ‘up to 12 SSN-AUKUS submarines’ and 12 F-35/A dual capable aircraft to form a contribution to NATO’s sub-strategic nuclear mission).

These major elements, which have always been regarded as the centrepieces of Defence reviews, will be produced as a Defence Investment Plan ‘in the autumn’. A Defence Reform & Efficiency Plan will be produced in the same timeframe, which will presumably explain how the newly reformed MOD plans to implement the conclusions of the review and the contribution efficiencies will make to its affordability.

So, ‘What do you think of the show so far?’ to quote the late Eric Morecombe.

Click here for the full press release